At the present time, machines employed for the production of mechanical energy by means of the expansion of compressed vapor or gas consist, primarily, of reciprocating engines and turbines. Reciprocating engines, often called "positive displacement" engines, employ the reciprocating motion of pistons and other mechanical components to accomplish the energy conversion process. In comparison, turbines are purely rotational machines which employ aerofoil-like lifting surfaces installed on a rotational armature to accomplish the energy conversion process. Both of these machines may feature the use of either externally produced or internally produced compressed gaseous or vaporous working fluid. Present day versions of these machines derived from early steam engine technology, the reciprocating engine from the inventions of Thomas Newcomen (1711), and James Watt (1763), and the turbine from the inventions of Dr. Gustav De Laval (1883) and Charles Parsons (1884). Over the last two centuries the basic products of these inventors have been developed to provide a range of prime power machines based upon a number of theoretical thermodynamic cycles such as stated by Carnot (1824), Rankine (1849), Breyton (1874), Otto (1876), and Diesel (1892).
In a general comparison reciprocating machines offers good control response and is favored for low to moderate (fractional horsepower to 5000 horsepower) power systems requiring rapid response to a wide range of power demands. However, their functional dependency upon reciprocating motion and mechanically actuated valve arrangements constrains the power density of these machines causes them to inherently feature undesirable characteristics of noise and vibration. The turbine offers the advantages of reduced mechanical complexity, superior power density and vibration free operation. However the power density of the turbine is substantially derived from its relatively high rotational speed and, therefore, turbines require transmission gearing systems with large reduction ratios to make them mechanically acceptable prime movers for most applications. The economic and inertial implications of this requirement is substantially the reason that turbine machinery is commonly preferred only for applications requiring a relatively steady state demand for large measures of power (500 horsepower to 50,000 horsepower).
Over a number of years significant inventive effort has been directed toward the derivation of "rotary" machines which would offer the performance and operational flexibility characteristics offered by reciprocating type machines without their attendant characteristics of mechanically produced noise and vibration. Patents granted for rotary energy conversion machines feature a variety of motion principles and rotational component concepts such as intermeshing and eccentrically rotating lobe type rotors, intermeshing gear type rotors, and radial vane (blade) type rotors. The invention presented in this disclosure is related to a radial vane type rotary machine as briefly described below.
The radial vane type rotary machine primarily consists of a stationary containment cylinder with a closure structure affixed at each end which enclose a rotational armature rigidly installed on a rotational shaft. The interior surface (bore) of the stationary containment cylinder is circular in cross section and cylinder wall is installed with ports such as to permit the movement of the working fluids, through its boundary at appropriate locations. The axial ends of the rotational shaft pass through rotational bearings installed in the containment cylinder end closure structures and are configured such as to provide the appropriate interfaces for imparting or extracting rotational energy from the device. The rotational shaft and armature are concentric and rotate on an axis which is parallel to, but radially displaced from, the axis of the containment cylinder. The armature is circular in cross section with a diameter significantly less than the bore diameter of the containment cylinder and is fitted with a number of equally spaced radial slots each of which is parallel to the axis of the armature. The slots are sized such as to provide structural support for a radial vane but allow relative sliding movement of the vane in axial and radial directions. The vanes project from the periphery of the armature such as to maintain contact with or remain in close proximity to the inside surface of the containment cylinder. The presence of the radial vanes subdivides the cavity between the peripheral surface of the armature and the inside surface of the containment cylinder into a number of segmental, annular, cells. Each cell is bounded by the armature periphery, the interior surface of the containment cylinder, two adjacent radial vanes, and the containment cylinder end structures. The radial displacement of the rotational axis of the armature from the longitudinal axis of the containment cylinder causes the radial distance between a reference point on the peripheral surface of the armature and the interior surface of the containment cylinder to be trigonometrically dependent upon the rotational position of the armature. This trigonometric dependency causes a cyclical variation the volume of any given segmental cell as the armature is rotated. The cyclical variation in segmental cell volume resulting from armature rotation fulfills the volumetric change requirements of Rankine and Carnot heat engine cycles. For any given cylinder length, the effective (swept) volume is directly related to: a) the difference between the inside diameter of the containment cylinder and the rotating armature, and b) the distance of separation between the longitudinal axis of the containment cylinder and the rotational axis of the armature. For any given effective volume, the compression (or expansion) ratio of the volumetric cycle is directly related to the number of segmental cells surrounding the armature.
The functional viability of all fluid compression machines is fundamentally dependent upon their capability to exceed thresholds for thermodynamic and mechanical efficiency while fulfilling particular requirements for effective fluid containment and the accommodation of thermally and/or mechanically induced structural deformations. In this regard radial vane type rotary machines introduce a number of issues each which requires careful consideration in the development of a functionally viable entity.
The thermodynamic efficiency of all fluid compression machines is directly related to the compression (or expansion) ratio of the volumetric cycle, and, as previously noted, the said ratio is directly related to the plurality of the segmental cells surrounding the armature. For this reason from a thermodynamic efficiency viewpoint, the functional viability of the radial vane machine is attained only when the plurality of radial vanes exceeds a certain minimum threshold.
Mechanical efficiency is essentially the measure of energy conservation exhibited by a mechanism in the process of doing work and, substantially, relates inversely to the quantity of energy dissipated by frictional interaction of dynamically related components. From a mechanical efficiency viewpoint functional viability is attained only when the relative magnitude of energy dissipation is less than a certain allowable threshold.
One unique mechanical efficiency problem presented by radial vane type rotary machines is the means for restraint of the radial vanes which, in the plurality necessary to satisfy thermodynamic efficiency requirements, create the preponderance of dynamically active mechanical interfaces. Early prior art for vane type rotary machine simply illustrates the radial vanes to be radially constrained by sliding or rolling contact between the radial vane and the containment cylinder or cam surfaces. Analysis demonstrates that the energy dissipation resulting from the combination of relatively large centripetal force and high relative speed makes such concepts non-viable from a mechanical efficiency viewpoint. Later art, as presented in recently awarded patents, illustrates methods for constraining the radial vanes by means of rotational vane end constraint devices which offer substantial improvement in mechanical efficiency.
The rotary vane machine also presents a unique problem in the need for a mechanically efficient means for effective gas sealing at the axial ends of the segmental cavities which surround the armature. The technical approach to the resolution of this issue as presented in prior art has essentially consisted of the incorporation of a minimized gap between axial ends of the rotating components and the inside surfaces of the containment cylinder end structures or radial vane constraint devices. Although this approach may be deemed technically viable for small radial vane rotary type liquid transfer pumps and compressed air driven motors the approach is deemed non viable for larger radial vane type rotary machines intended to function with high values of fluid temperature and pressure in which non uniform distributions in thermal and pressure loading may cause mechanically significant dimensional changes in the machine components. A device which offers the capability for maintaining an effective seal at the axial ends of the segmental cavities while elastically responding to thermally and mechanically induced dimensional changes in the machine components is the subject of this disclosure.
A number of cases of prior art as particularly related to the instant disclosure are briefly reviewed below:
U.K. Pat. No. 114,584 issued to Frank Lyon on Apr. 18, 1918 discloses a means by which the vanes are radially constrained by flanges on a pair of rotating disks one of which is installed, on low friction rotational bearings, at each end of the containment cylinder. Sealing at the ends of the segmental cavities is accomplished by contact between the inside surface of the disk and the ends of the rotating vanes and rotating armature. No means is provided to account for variations in the axial lengths of the interfacing components due to thermal expansion or other causes.
Republic of France Pat. No. 753.431 issued to M. Bernhard Bischof on Oct. 16, 1933 discloses a means by which each radial vane is radially constrained by a pair of shoe like components one of which is installed at each of the axial extremities of the vane and which slide upon a lubricated bearing ring installed at each end of the containment cylinder. The axial ends of the vanes maintain sliding contact with the inside faces of the containment cylinder end structures and no means is provided to account for variations in the axial lengths of the interfacing components due to thermal expansion or other causes.
U.S. Pat. No. 2,414,187 issued to Erling Borsting on Jan.14, 1947 discloses a means by which each radial vane is radially constrained by a pair of shoe like components, one of which is installed at each of the axial extremities of the vane, which bear upon the rim flanges of a pair of rotating disks one of which is installed, on low friction rotational bearings, at each end of the containment cylinder. Sealing at the ends of the segmental cavities is accomplished by contact between the inside surface of the disk and the ends of the radial vanes and the rotating armature. No means is provided to account for variations in the axial lengths of the interfacing components due to thermal expansion or other causes.
Commonwealth of Australia Pat. No. 136,185 issued to Sydney Edgar Willet et.al on Feb. 16, 1950 discloses a means by which the vanes are radially constrained by sliding contact with the inside surface of the containment cylinder. Sealing at the ends of the segmental cavities is accomplished by sliding contact between the ends of the radial vanes and the rotating armature and the inside surfaces of a pair of non rotating disks one of which is installed at each end of the containment cylinder. The disks are spring loaded to such as to account for variations in the axial lengths of the radial vanes due to thermal expansion or other causes.
U.S. Pat. No. 2,590,132 issued to F. Scognamillo on Mar. 25, 1952 discloses a means by which the radial vanes are radially constrained by a pair cylindrical extensions one of which is installed at each of the axial extremities of each vane and which engages a socket installed in a rotating disk at each end of the containment cylinder. No means is provided to account for variations in the axial lengths of the interfacing components due to thermal expansion or other causes.
U.K. Pat. No. 577,569 issued to John Meradith Rubary on Aug. 20, 1952 discloses a means by which the vanes are radially constrained by flanges on a pair of rotating disks one of which is installed, on low friction rotational bearings, at each end of the containment cylinder. Sealing at the ends of the segmental cavities is accomplished by contact between the inside surface of the disk and the ends of the radial vanes and the rotating armature. No means is provided to account for variations in the axial lengths of the interfacing components due to thermal expansion or other causes.
U.S. Pat. No. 3,360.192 issued to Adrian Van Hees on Dec. 26, 1967 discloses a means by which the vanes are radially constrained by flanges on a pair of rotating disks one of which is installed, on low friction rotational bearings, at each end of the containment cylinder. Sealing at the ends of the segmental cavities is accomplished by contact between the inside surface of the disk and the ends of the rotating vanes and rotating armature. No means is provided to account for variations in the axial lengths of the interfacing components due to thermal expansion or other causes.
Japanese Pat. No. 63-9685 issued to Nippon Piston Ring Co. Ltd. (Yukio Suzuki) on Jan. 16, 1988 discloses a means by which the radial vanes are radially constrained by flanges on a pair of rotating disks one of which is installed, on low friction rotational bearings, at each end of the containment cylinder. Sealing at the ends of the segmental cavities is accomplished by contact between the inside surface of the disk and the ends of the radial vanes and the rotating armature. No means is provided to account for variations in the axial lengths of the interfacing components due to thermal expansion or other causes.
None of the disclosures taken singly or combination describe the invention as claimed in this disclosure.